Bucket_selector on nested agg bucket doesn't works - elasticsearch

Question

I'm trying to make an aggregation on a sibling's children aggregation to filter bucket based on a requested quantity condition, so here is my query :
GET _search
{
"size": 0,
"query": {
"bool": {
"must": [
{
"terms": {
"product.id": [20,21,22,23,24]
}
}
]
}
},
"aggs": {
"carts": {
"terms": {
"field": "item.cart_key"
},
"aggs": {
"unique_product": {
"terms": {
"field": "product.id"
},
"aggs": {
"quantity": {
"sum": {
"field": "item.quantity"
}
}
}
},
"filtered_product_quantity": {
"bucket_selector": {
"buckets_path": {
"productId": "unique_product.key",
"productQuantity": "unique_product>quantity"
},
"script": {
"params": {
"requiredQuantities": {
"20": null,
"21": null,
"22": null,
"23": 3,
"24": null
}
},
"lang": "painless",
"source": "params.requiredQuantities[params.productId] <= params.productQuantity"
}
}
}
}
}
}
}
And the error :
{
"error": {
"root_cause": [],
"type": "search_phase_execution_exception",
"reason": "",
"phase": "fetch",
"grouped": true,
"failed_shards": [],
"caused_by": {
"type": "aggregation_execution_exception",
"reason": "buckets_path must reference either a number value or a single value numeric metric aggregation, got: [Object[]] at aggregation [unique_product]"
}
},
"status": 500
}
Here is a sample document set :
[
{
product.id: 12,
item.cart_key: abc_123,
item.quantity: 2
},
{
product.id: 11,
item.cart_key: abc_123,
item.quantity: 1
},
{
product.id: 23,
item.cart_key: def_456,
item.quantity: 1
}
]
Is it the appropriate aggregation in use ?
In other way, I would like to :
Aggregate my documents by cart_key.
Per product.id , sum the quantity
Filter aggregations that have a quantity higher than a given Record object {[product.id]: minimum_quantity} (here is the requiredQuantities param
I don't know if the source script will works as elasticsearch can't reach it.

Answer 1

I don't think you handle the problem correctly, but here an hacky working solution
{
"size": 0,
"aggs": {
"carts": {
"terms": {
"field": "item.cart_key"
},
"aggs": {
"unique_product": {
"terms": {
"field": "product.id"
},
"aggs": {
"quantity": {
"sum": {
"field": "item.quantity"
}
},
"hackProductId": {
"max": {
"field": "product.id"
}
},
"filtered_product_quantity": {
"bucket_selector": {
"buckets_path": {
"productQuantity": "quantity",
"productId": "hackProductId"
},
"script": {
"params": {
"requiredQuantities": {
"12": 0,
"11": 0,
"22": 0,
"23": 0,
"24": 0
}
},
"lang": "painless",
"source": "params.requiredQuantities[((int)params.productId).toString()] <= params.productQuantity"
}
}
}
}
}
}
}
}
}